This is a module of instances of RegexContext. Nothing else is
exported. These work for all the front ends and backends
interchangably. These instances are important because they provide
the different results that can be gotten from a match or matchM
operation (often via the =~ and =~~ operators). The name is Context
because they are context dependent: use them in a context that expects
an Int and you get a count of matches, use them in a Bool context and
get True if there is a match, etc.

( RegexLike a b => RegexContext a b Bool ) :
Whether there is any match or not

( RegexLike a b => RegexContext a b () ) :
Useful using =~~ in a monad, since failure to match is via fail

( RegexLike a b => RegexContext a b (MatchOffset,MatchLength) ) :
This returns the initial index and length of the whole match.
Starting at (-1) indicates failure to match.

( RegexLike a b => RegexContext a b b ) :
This returns the text of the whole match.
It will return empty from Extract if there is no match.
These are defined in other modules, but documented here for convenience.

( RegexLike a b => RegexContext a b MatchArray ) :
Where each sub-part the match starts and its length.
Starting at (-1) indicates unused.

( RegexLike a b => RegexContext a b (b, MatchText b, b) ) :
The text before the match, the details of the match, and the text after the match

( RegexLike a b => RegexContext a b (b, b, b) ) :
The text before the match, the text of the match, the text after the match

( RegexLike a b => RegexContext a b (b, b, b, [b]) ) :
The text before the match, the text of the match, the text after the match, and the text of the 1st and higher sub-parts of the match. This is the same return value as used in Text.Regex.

These instances are for all the matches (non-overlapping). Note that backends are supposed to supply RegexLike instances for which matchAll and matchAllText stop searching after returning any successful but empty match.

( RegexLike a b => RegexContext a b Int ) :
The number of matches

These instances similar to the single match ones above, but in a List:

( RegexLike a b => RegexContext a b [(MatchOffset, MatchLength)] ) :

( RegexLike a b => RegexContext a b [b] ) :
As a policy, I chose [b] to be the list of whole text of each match.

( RegexLike a b => RegexContext a b [MatchArray] ) :

( RegexLike a b => RegexContext a b [Array Int b] ) :

( RegexLike a b => RegexContext a b [MatchText b] ) :

( RegexLike a b => RegexContext a b [[b]] ) :
This is the list of the list of the text of the sub-part of each match.
Unused matches are empty (defined via Extract)